La Niña weather pattern expected this fall

Southwest weather is likely to be warmer and dryer through fall and winter as the El Niño phenomenon transitions to La Niña, according to National Weather Service spokesman Matt Groh.

Groh told participants in the recent Big Country Wheat Conference in Abilene that El Niño began to weaken “rapidly early last spring and transitioned to neutral by late spring as water in the equatorial Pacific Ocean began to cool.

“Continued cooling through fall and winter supports a transition to a moderate to strong La Niña with typically below normal precipitation and above normal temperatures.”

Groh said temperatures from September through November are likely to be above normal and precipitation is likely to be less than normal. Historical records, Groh said, dating back to the 1950s support the weather predictions associated with La Niña and El Niño. Weather stations in Abilene, Rotan, San Angelo and Brady, Texas offer sound data on precipitation.

“If we compare average winter precipitation for a year with a moderate to strong La Niña effect to normal winter precipitations we see a pattern for all four sites,” he said. “Average winter precipitation is below normal and below the 30-year normal.

“Data also show a pattern of increased precipitation with a weak to moderate El Niño. El Niño into last winter resulted in significantly increased precipitation levels.”

Groh said La Niña could also create conditions ideal for wildfires, “especially following a year with good rainfall and good growth of grasses. Those grasses dry down and create a fuel source.”

Weather is complicated, however, and Groh said no two seasons are ever alike and patterns may vary.

“But La Niña is likely to continue through this fall and winter and will increase the probability of temperatures above normal and precipitation below normal.”